Debt Obligations (Changes In The Liability And Equity Components Of Convertible Senior Notes) (Details) (USD $) In Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2011		Dec. 31, 2010		Oct. 19, 2011	Mar. 31, 2008
Debt Instrument [Line Items]
Net Carrying Amount	$ 2,213		$ 2,321
2.50% Convertible Senior Notes Due August 15, 2013 [Member] | Liability Component [Member]
Debt Instrument [Line Items]
Principal Balance	428.0		428.0
Unamortized Debt Discount	29		40
Accretion of Debt Discount, Unamortized Debt Discount	(11)
Accretion of Debt Discount, Net Carrying Amount	11
Net Carrying Amount	399		388
2.50% Convertible Senior Notes Due August 15, 2013 [Member] | Equity Component [Member]
Debt Instrument [Line Items]
Gross Equity Component	80		80
Deferred Taxes	32		32
Net Equity Component	48		48
2.50% Convertible Senior Notes Due August 15, 2013 [Member]
Debt Instrument [Line Items]
Principal Balance	428.0		428.0		335.0	475.0
Unamortized Debt Discount	29		40
Net Carrying Amount	399	[1]	388	[1]
Net Equity Component	$ 48		$ 48

[1] See "2.50% Convertible Senior Notes" below for further discussion.